I just noticed some black grease coming out of my 10 year old Aqua Drive plus it has started making a bit of noise at low revs. Any suggestions as to what I can do to remedy this problem?

Sounds like the rubber boot that holds the grease in to lubricate the universal joint has failed or the clamps at either end of the boot have let go.

I've got a 24 year old aqua drive in my boat & the previous owner advised to lightly lubricate the boot with lanolin occasionally to help stop the rubber/neoprene perishing or abrading (If you drive line has a large angle change through the aqua drive, it could be that the corrugations on the boot on the inside of the angle rub together with every revolution....)

You need to be careful not to put too much lanolin on it as it will spin off & make a mess...

Could be common problem with the aqua drives as my boat came with a spare boot and evidence of grease in the engine bay from a previous failure!!

Don't worry too much about the grease spewing. What happens is that the bolts (Allen key bolts) come loose. Tighten them and listen if strange sounds go away. If so, take each bolt out in turn, clean it's threads plus the female thread and use high strength thread locker (like permatex red) to put it back. Medium strength will not lock it nor will red if the threads aren't clean. Check these bolts periodically as they are notorious for loosening.

If the strange sounds do not go away, check if they actually come from the aquadrive cv joint and not from the gearbox or something else. If they come from the aquadrive, check if the engine mounts are still okay. If they are, I would advise to buy a new cv joint and have the old one overhauled and stowed as a spare. Overhaul kit isn't expensive and easy to do yourself.

I checked the rubber and it appears to be fine. I don't see any grease any where in side the fitting it sits in. I checked all the allen bolts and they are rock tight. No give or movement to them at all. I cleaned the outside of the fitting of what grease there was and off the channel under the shaft and will look again tomorrow once we set off again to see if any more grease comes out.

At 700 rpms,it makes a good bit of noise but at 800, it runs nice and smooth. I had a new transmission installed at 4320 hours and have now 4471 hours on the engine(blew it a few months ago). I've already changed the transmission fluid since the install so it has good fluid in it.

Any suggestions? I'll keep monitoring it to see of anything changes. I'm a long way from where the new transmission was installed for warranty work.

Well, if you get more grease splattering with the allen bolts tight and the noise at 800, I think you better check further into it. What is the angle the shafts make at the CV joint? Is that within spec's for your engine hp? Check for grease splatter while in your slip; you might be able to determine exactly where it's coming from. What I always saw is a straight line of grease-splatters on both sides of the joint. The leak is where they meet at the joint.

The unit has been in the boat for the past ten years with no problems. The grease is coming out of the two extra holes where it bolts onto the transmission plate. I cleaned them up and will monitor the space around it for more grease today as well as more noise. At 750revs, it make some noise--or could be the new transmission. At 800 and up, it's fine and runs smoothly.

Am I doing any damage running it with the grease coming out? Sort of concerns me when grease comes out of a fitting.

Okay, your problem is different from the regular issue with the Aquadrive's where the grease comes out when the allen bolts come loose.

At 10 years without problems I think it's time you order an overhaul kit. When you have received it, take the CV joint off and put it on a bench. Open it up, clean all the grease out and visually check the two joints for wear and tear. If they look good, wash all the old grease and dirt (metal particles too) out with kerosine/paraffin (it's the same stuff but called different around the world... lamp-oil is the same too) until it's 100% clean and dry. Then you put the new grease and parts from the overhaul kit in.

Before you open it up, turn it with your hands holding it at about the same angles as when it's installed. See if you feel any hard spots. These should go away after cleaning and re-greasing. If they don't go away, you need to replace the unit.

That is why I advise to ask for a quote for both an overhaul kit and a whole new CV joint. You can install the new one and check out the old one. If it's still good, overhaul it and store as a spare. The CV joint is a weak part of the transmission line so it's not a waste to have a spare (we do and overhauled each one already).